Find the number of permutations of four letters from the word MATHEMATICS.
There are 2 of M,A and T, So we have to divide the permutations by . or do I find the number of permutations with two pairs of letters, and permutations with one pair of letters, and the number of permutations without any pairs of letters?
oops wrong there, it should be 11-3=8, we have 1680. we take away the repeated letters right?
the one where two pairs is also wrong because the next question after this asks how many of the permutations contain to pairs of letters that are the same and the answer is 18, but i don't know how that is arrived at.
i'm going wrong somewhere here because the answer is supposed to be 2454.